The use of woven geotextiles in the stabilization and reinforcement of roadways, embankments, and retaining walls is common today.
More than 20 years ago, The American Association of State Highway and Transportation Officials (AASHTO) issued Specification M 288, which described the use and qualifications of geotextile fabrics for highway applications. That document detailed the basic requirements for fabrics used in the separation, stabilization, erosion control, and subsurface drainage for roadways. There, fabrics were expressed as belonging to three classes, with Class 1 designated for severe or harsh installation conditions and Classes 2 and 3 specified for less severe conditions. Class 2 woven geotextiles are typically made with monofilaments, and Class 3 woven geotextiles are typically made of slit yarns or tapes of highly oriented polypropylene.
The fabrics in the AASHTO M 288 document were specified based on the minimum properties related to fabric performance—such as grab strength, tear strength, and apparent opening size—rather than fabric basis weight. The AASHTO property profiles have been widely accepted within the road building community. Because woven geotextile fabrics can be more expensive than the materials they replace in a roadway, manufacturers have sought to produce such fabrics at the lowest possible cost.
One way to minimize cost of woven geotextile polymer fabric is by reducing the amount of polymer used to make the woven geotextile fabric, since the cost of the polymer is a major component of the finished woven geotextile fabric cost. For this approach to be successful, the required level of performance must be achieved with a woven geotextile fabric having a reduced basis weight. In terms of strength requirements, the woven geotextile fabric strength-to-weight ratio (STVVR) must be increased. The ability to increase woven geotextile fabric STVVR can be shown by either meeting a specific fabric strength requirement using a woven geotextile fabric with reduced weight, or by demonstrating higher strengths at equivalent fabric weight.
Since the introduction of the AASHTO M 288 specification, much effort has gone into optimizing fabrics to meet the required property profiles. Those efforts address a longstanding and continuing need to develop woven geotextiles that meet the required property profiles at lowest cost.
The need also exists for increased woven geotextile fabric strength and stiffness at the lowest possible cost for applications not covered by the AASHTO M288 specification, such as roadway reinforcement and mechanically stabilized earth systems.